Various methods have been known for generating gas plasma. Among such methods, a method of generating inductively coupled plasma by using a high-frequency power has been known as a method of obtaining uniform plasma at an extremely high density in a plasma generating chamber. Recently, it has been attempted, e.g., to increase a frequency of a high-frequency power to be applied for improving plasma characteristics.
For the production of such inductively coupled plasma, a high-frequency power is applied to a high-frequency antenna provided for the plasma generating chamber, and the high-frequency antenna is generally arranged outside the plasma generating chamber.
However, Japanese Laid-Open Patent Publication No. 2001-35697 (JP2001-35697A) has proposed a structure, in which the high-frequency antenna is arranged inside the plasma generating chamber for improving utilization efficiency of high-frequency power. For suppressing abnormal discharge and others which may occur when the antenna is arranged inside the plasma generating chamber, the antenna has a planar (two-dimensional) structure formed of a wire-like conductor terminated without circling, and thereby the inductance of the antenna is reduced. Further, in this structure, the antenna is extended outside from the plasma generating chamber, and its termination is grounded via a blocking condenser.
However, according to the proposed high-frequency antenna arranged in the plasma generating chamber, if a frequency of the applied high-frequency power is raised for improving plasma characteristics such as plasma density and others, the inductance of the antenna is still high, e.g., due to the fact that the antenna termination is extended outside from the plasma generating chamber, and therefore such a disadvantage occurs that matching cannot be achieved.
Since the antenna termination is extended outside from the plasma generating chamber, a gas-tight structure must be formed at a portion where the termination passes through a wall of the plasma generating chamber.
Since the antenna has a planar structure, the antenna may be arranged near the chamber wall for efficiently utilizing an inner space of the plasma generating chamber, and this arrangement is probably employed in many cases. According to this arrangement, a large portion of the high-frequency electric field applied from the antenna is directed to the chamber wall, and this lowers the utilization efficiency of the high-frequency power.
Accordingly, an object of the invention is to provide a plasma generating device provided with a plasma generating chamber and a high-frequency antenna arranged in the plasma generating chamber for generating inductively coupled plasma by applying a high-frequency power to a gas in the plasma generating chamber from the high-frequency antenna, and particularly to provide a plasma generating device which can reduce an inductance of the high-frequency antenna and can generate desired plasma by suppressing disadvantages such as abnormal discharge, matching failure and others as compared with the same kind of conventional device, and can generate the desired plasma by suppressing disadvantages such as abnormal discharge, matching failure and others even when a frequency of the high-frequency power to be applied is raised for improving the plasma characteristics.
Another object of the invention is to provide a plasma generating device which can achieve the above object, and can perform intended processing such as film deposition.